r300: another fix for reader detection in the presence of loops

This helps in some cases where we fail to detect that the write mask
is still alive after the loop and thus fail to detect some readers.

Signed-off-by: Pavel Ondračka <pavel.ondracka@gmail.com>
Reviewed-by: Filip Gawin <filip@gawin.net>
Tested-by: Filip Gawin <filip@gawin.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19618>
1 file changed